Thanks, Al, for the microcode rom dumps (however the 12823-80020.bin, F-SIS is missing - lost somehow during copying?). -- It should be there now I've seen that the base ROMs slightly differ from the microcode listing in the 2109-90004_1000EF_uPrgRef_Apr80.pdf from your site. What is the relation between both sets? -- The set that is up there was the last released set, and uses x8 proms instead of x4. Release histories of the firmware can be found starting on page 33-1 of the CE manual. I've hacked together a simple microcode disassembler for these ROMs, with the exception of the 1816-* ROMs that I do not know how to handle (any further info?). -- That is the MX IOP firmware. They are x4 parts (256x4, 82S129's to be exact) I suspect Bob Supnik or Mike Gemeny may already have disassemblies of that.